The invention relates to a rotary evaporator having a device stand, from which a guide tower projects, said guide tower has a holder, on which an evaporation vessel is held so as to be pivotable about a horizontal pivot axis and which comprises a holding part which is connected to the guide tower, is movable laterally of the guide tower in the longitudinal direction thereof and on which a carrying part, which is connectable to the evaporation vessel, is held so as to be pivotable about a horizontal pivot axis.
Different designs of rotary evaporators are already known. Such rotary evaporators are intended for the gentle separation of liquid mixtures and solutions utilizing the variable boiling points of the components. Thus, rotary evaporators can also be utilized for drying, for solvent recovery and for similar processes. A heating bath in which a heated volume of water or oil is situated regularly serves as an evaporator element. An evaporator piston, which includes the solution to be evaporated in its piston interior, rotates in the heated water or volume of oil in the heating bath. Said solution is distributed on the heated inside walls of the piston of the rotating evaporator piston as a thin liquid film which can easily evaporate there. As a result of the rotation of the evaporator piston delay in boiling is also avoided and in conjunction with the heating bath a homogeneous temperature distribution is obtained in the medium to be evaporated. The additionally brought about thorough mixing of the heating bath facilitates the regulating of the effective heating temperature in a considerable manner. To avoid high temperatures which are linked to risks for the user and can also produce unwanted chemical reactions in the medium, the evaporating process is supported by an evacuating of the process chamber. The evaporator capacity is varied as a result of the temperature of the heating bath, the size of the piston and the speed of rotation of the evaporator piston as well as of the vacuum pressure set. On account of the general inertia of the temperatures of the medium and the process, the evaporation at constant temperatures is primarily controlled by the pressure. In order to be able to evacuate the process chamber, and in order to be able to connect the necessary coolant inflows and outflows to the required cooler, at least one hose connection, and regularly several hose connections which are connected to a vacuum pump or to a coolant inflow or outflow in each case by means of a flexible hose line, is provided on the glass assembly of the rotary evaporator which includes the evaporator piston.
Over the past decades, the usability, the safety and the automation of previously known rotary evaporators has been improved in a considerable manner. Occasionally, however, some disadvantages can be ascertained.
GB 2171922 has already previously made known a rotary evaporator of the type mentioned in the introduction with a device stand from which projects a guide tower which has a holder on which an evaporation vessel is held so as to be pivotable about a horizontal axis. The holder comprises a holding part which is connected to the guide tower and is movable laterally of the guide tower in the longitudinal direction thereof. A carrying part which is connectable to the evaporation vessel is held on the holding part so as to be pivotable about a horizontal pivot axis, a locking screw which comprises an adjusting head or similar handle on its one screw end for manual activation being provided to adjust and secure the chosen pivot position. The previously known rotary evaporator can be adapted to the different dimensions of various evaporation vessels, but the device structures realized with the previously known rotary evaporator are no longer able to be reproduced easily at a later time.
EP 0 156 937 A1 has previously made known a rotary evaporator which has a plate-shaped device stand. A tower, on the free tower end of which a pivot arm serving as a holder is pivotably mounted, projects above the device stand. An evaporation vessel is held on the arm end of the pivot arm remote from the tower so as to be rotatable about its longitudinal axis. By pivoting the pivot arm the evaporation vessel is arbitrarily adjustable between two end positions such that as a result of immersing the evaporation vessel at different depths into the water bath different quantities of heat can be supplied or the supply of heat is interrupted. In order to be able to immerse the evaporation vessel into the water bath or lift it out of the water bath and in order to be able to modify the height of the evaporation vessel for this purpose, the pivot arm serving as a holder is pivotable electromechanically, pneumatically or hydraulically between two end positions in both pivot directions and securable in each case in the chosen pivot position. In this case, an embodiment described in EP 0 156 937 A1 provides that the pivot arm is pivotable by means of a threaded spindle which cooperates with the pivot arm. The pivot arm is pivoted to adjust the evaporation vessel vertically. Insofar as a spindle drive with an adjusting spindle is provided in EP 0 156 937 A1, said spindle drive is provided for pivoting the pivot arm.
In the case of the previously known rotary evaporators, a holder, on which an evaporation vessel, which is realized in the majority of cases as an evaporation piston, is held so as to be pivotable about a horizontal pivot axis, is provided on the guide tower projecting above the device stand. This holder is secured on the guide tower in the majority of cases by way of a screw connection which has to be released prior to the pivoting of the holder and retightened again after the pivoting. In this case, there is the risk of the glass assembly, which is fastened on the holder and also includes the evaporation vessel, falling into the stop such that the fracture-sensitive evaporation vessel which is additionally under vacuum can break. The awkward pivotability of the holder provided on previously known rotary evaporators makes changing the evaporation vessels and exchanging a larger or smaller evaporation vessel difficult, which can also possibly make it necessary to modify the pivot angle. The exchanging of larger or smaller evaporation vessels is also additionally made more difficult as a result of the exchanged evaporation vessel having to be able to be properly immersed into the heating bath situated in the tempering vessel of the rotary evaporator, it only being possible to take the different dimensions of the various evaporation vessels into account by changing the lifting height and the pivot angle.